Climate Bulletin For Sri Lanka (20 November 2020)

              Highlights                             

 • The NOAA weekly rainfall forecast predicts Between 18th-24th Nov: high rainfall over the Eastern Province the drop in rainfall over the rest of the country.

 • Cyclonic circulation has emerged in the Bay of Bengal and it is predicted to intensify and track several hundred to the North-East of Sri Lanka on the 25^th of November. 

 • Between 11th - 17th Nov: up to 200 mm in Puttalam and Kurunegala districts on 15th  Nov.

 • MJO shall severely enhance the rainfall during 17^th – 26^th Nov and slightly enhance during 27^th Nov - 1^st Dec over Sri Lanka.

 • From 10th - 16th Nov: up to 8 km/h  Easterly winds were experienced by the entire island.

 • 0.50C above-average sea surface temperature was observed in the seas around Sri Lanka which shall likely change as the La Nina sets in more fully.

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Monitoring

Rainfall

Weekly Monitoring:

Date	Daily Maximum Rainfall
11th November	Up to 50 mm in Colombo and Kalutara districts.
12th November	Up to 70 mm in Puttalam and Kurunegala districts.
13th November	Up to 180 mm in Kurunegala and Gampaha districts.
14th November	Up to 40 mm in Kandy, Ratnapura, Kalutara, Galle and Matara districts.
15th November	Up to 200 mm in Puttalam and Kurunegala districts.
16th November	Up to 40 mm in Mannar, Vavuniya, Polonnaruwa, Trincomalee, Batticaloa and Hambantota districts.
17th November	Up to 70 mm in Kurunegala district.

Total Rainfall for the Past Week: 

The RFE 2.0 tool shows total up to 200 – 300 mm in Gampaha, Kegalle, Kurunegala and Puttalam districts; up to 150 – 200 mm in Kalutara, Colombo and Ratnapura districts; up to 100 – 150 mm up to in Galle, Matara, Nuwara Eliya, Kandy, Matale and Anuradhapura districts; up to 75 – 100 mm in Polonnaruwa, Batticaloa, Moneragala and Mannar districts; up to 50 -75 mm in Hambantota, Badulla, Amapara, Trincomalee, Vavuniya, Mullaitivu, Kilinochchi and Jaffna districts.

Above rainfall average up to 200 – 300 mm in Kurunegala, Puttalam and Gampaha districts; up to 100 – 200 mm in Colombo, Kalutara, Kegalle and Ratnapura districts; up to 50 – 100 mm in Galle, Kandy, Matale, Nuwara Eliya, Anuradhapura and Mannar districts; up to 25 – 50 mm in Matara, Polonnaruwa and Vavuniya districts; up to 10 – 25 mm in Hambantota, Moneragala, Badulla, Batticaloa, Trincomalee, Mullaitivu and Kilinochchi districts; Below rainfall average up to 25 – 50 mm in Ampara, district. 

Monthly Monitoring: 

During October – Above average rainfall conditions up to 4 mm in Vavuniya, Anuradhapura, Badulla, Ampara and Moneragala districts; up to 2 mm in Mannar, Batticaloa, Ratnapura and Hambantota districts; Below average rainfall up to 8 mm in Galle, Kalutara and Colombo district; up to 6 mm in Matara, Gampaha, Kegalle, Nuwara Eliya, Kandy, Kurunegala, Puttalam, Jaffna districts; up to 4 mm in Kilinochchi, Mullaitivu, Polonnaruwa, Matale and Trincomalee districts. 

 Predictions

Rainfall

14-day prediction: 

NOAA NCEP models: 

From 18^th – 24^th November: Total rainfall up to 115 mm in East of the island; up to 105 mm rainfall in Northeast of the island; up to 85 mm rainfall in North, Central and Southeast of the island: up to 75 mm in Southwest of the island; 65 mm in Northwest and Southwest of the island and 55 mm in west of the island.

From 25^th November – 1^st December: Total rainfall up to 115 mm in Northeast of the island; up to 105 mm rainfall in East and North of the island; up to 85 mm in Northwest, Central and West of the island; up to 55 mm in South, Southwest and Southeast of the island.

IRI Model Forecast: 

From 24^th – 29^th September: Total rainfall up to 75 mm in Badulla district; up to 50 mm in Ampara, Moneragala, Ratnapura, Nuwara Eliya, Kandy, Matale, Polonnaruwa, Anuradhapura, Batticaloa, Trincomalee, Vavuniya, Mullaitivu, Kilinochchi and Jaffna districts; and up to 25 mm in Mannar, Puttalam, Kurunegala, Kegalle, Gampaha, Colombo, Kalutara, Galle, Matara and Hambantota districts. 

MJO based OLR predictions:

For the next 15 days: 

MJO shall severely enhance the rainfall during 17^th – 26^th Nov and slightly enhance during 27^th Nov - 1^st Dec over Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific sea state: November 11, 2020 

Equatorial Eastern Pacific SST reached La Niña threshold in mid-November, and the atmospheric variables were either ENSO-neutral or indicative of weak La Niña conditions. 

Indian Ocean State

0.5 ⁰C above average sea surface temperature was observed in the seas around Sri Lanka.